Lateral flow assay reader based on human perception and method relating thereto

ABSTRACT

An instrument for reading a lateral flow assay device by detecting color changes based on human perception includes an optics module having a camera, a signal processor, a storage memory and a comparator circuit. The storage memory has stored therein a dataset of sample readings of reference assay devices similar in structure and function to that of the lateral flow assay device. The sample readings are based on human visual perceptions of colorimetric changes in the detection zones of the reference assay devices. The comparator circuit compares the measured colorimetric data relating to the assay device read by the instrument with the stored database of sample readings based on human visual perceptions of the colorimetric changes of the reference assay devices, and generates a comparison signal which is provided to the signal processor. The signal processor generates a determination signal indicative of the presence, absence or quantity of an analyte.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. Provisional Application Ser. No.62/428,174, filed on Nov. 30, 2016, and entitled “Lateral Flow AssayReader Based on Human Perception and Method Relating Thereto”, thedisclosure of which is incorporated herein by reference and on whichpriority is hereby claimed.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to devices and methods fordetermining the presence, absence or quantity of an analyte in a liquidsample, and more specifically relates to a reader used to detect colorchanges in a lateral flow assay device and methods relating thereto.

Description of the Prior Art

Lateral flow assay devices 2 are well known in the art and are usedextensively in the human medical and veterinary fields for testing ablood sample (i.e., whole blood, plasma or serum) or other bodily fluid(e.g. urine, saliva, milk etc.) for the presence, absence or quantity ofa one or more target analytes. Target analytes can include, for example,antibodies, antigens, hormones, small molecules, drug residues and thelike. When testing for antibodies or antigens, the presence of suchmarkers is typically an indication of an infectious disease in thepatient whose blood is being tested. One example of such a lateral flowassay device 2 is disclosed in U.S. Pat. No. 4,943,522, which issued toRobert W. Eisinger, et al. Another example of a lateral flow assaydevice 2, structured to effect a bi-directional capillary flow of asample, is disclosed in U.S. Pat. No. 5,726,010, which issued to ScottM. Clark, the latter patented device being manufactured or distributedby IDEXX Laboratories, Inc. of Westbrook, Me. under the trademark SNAP®.Other examples of lateral flow assays, such as those that use colloidalgold for visual indication of the presence, absence or quantity of atarget analyte, are well known and documented in the prior art. Thedisclosure of each of the aforementioned patents is incorporated hereinby reference.

Many such lateral flow assay devices 2 exhibit a human perceptiblecolorimetric change in an exposed viewing or read area of the device 2as an indication of the presence, absence, or quantity of an analyte inthe blood sample. In the SNAP® device, a wash buffer and substratesolution are used to enhance the visible perception of color changes inthe read area of the device. The wash solution removes any unboundcomponents, sample debris and unreacted conjugate reagent from the flowmatrix of the device 2, leaving a substantially clean, white backgroundin the read area of the device 2. The substrate solution causes anenzymatic reaction which results in a distinct blue-colored dot, ordots, in the read area of the device 2 that are easy to observe againstthe background of the white-colored matrix. Lateral flow devices thatutilize colloidal gold as a marker typically have a reddish/brown colorwhen the particles accumulate at the test and/or control line.

FIG. 1 of the drawings is a top view of a portion of a SNAP® 4Dx® Pluslateral flow assay device 2 used for screening dogs for six vector-bornediseases. In the read area 4 of the device 2, a blue dot 6 appearing inthe upper section indicates the presence of A. phagocytophilum/A. platysAb in the sample being tested. The blue dot 8 on the right side of theread area 4 (when the device 2 is viewed from the front) indicates thepresence of Heartworm Ag in the sample. A blue dot 10 in the lowercenter portion of the read area 4 of the device 2 indicates the presenceof Lyme disease Ab, and a blue dot 12 on the left side of the read area4 (when the device 2 is viewed from the front) indicates the presence ofE. canis/E. ewingii Ab. In the upper left corner of the read area 4 ofthe device 2, there is located a positive control spot 14 which willturn blue if the device 2 is working properly.

There also exists instruments which read the lateral flow assay devices2 and render an evaluation of the tests being performed, rather thanhaving a human visually determine from the indicator or detection dots6, 8, 10, 12 whether the test results are positive or negative. Forexample, the SNAP® Reader analyzer, manufactured and distributed byIDEXX Laboratories, Inc., is an image-analysis instrument which includesa digital camera. The analyzer stores and processes images of SNAP®tests according to the protocol of the specific, individual SNAP® testsdesigned for use with the analyzer. The SNAP® Reader analyzer then usescustom software to evaluate the results of the tests being run andreports the results. The analyzer takes digital pictures as test resultsare developing, and the software of the analyzer uses algorithmsspecific to the test to calculate the test results from these digitalimages. Other analyzers exist for reading lateral flow devices based oncolloidal gold technology, such as: DCN Technologies, Carlsbad, Calif.;and the ESEQuant™ lateral flow reader from Qiegen NV, Venlow,Netherlands.

Although prior art assay readers provide a quick and easy, and highlyreliable, indication of the presence, absence or quantity of an analyte,in practice, there may be situations when a result may be difficult todiscern. For example, with respect to device 2, the blue detection dotor dots 6, 8, 10, 12 may not be fully formed; that is, they may becrescent-shaped, rather than completely circular. Or, the dots 6, 8, 10,12 may be intermittently colored, for example, exhibiting bluedisconnected speckles. There are times when the detection dots 6, 8, 10,12 may be only lightly colored. Similar situations occur with colloidalgold lateral flow devices. The prior art analyzer's software will applyalgorithmic rules to the digital images taken by the camera of the readarea which are analyzed, and make determinations as to whether the bloodsample tested contains a target analyte, or whether the results areindeterminate and new tests need to be performed. The deterministicrules applied by the analyzer's software in the prior art are generallyhighly accurate, but are not based on human perception, to which thepresent invention relates.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide an instrument forreading a lateral flow assay device based on human visual perceptions ofcolorimetric changes in the device.

It is another object of the present invention to provide a method forreading a lateral flow assay device by detecting color changes theretobased on human perception.

It is yet a further object of the present invention to provide a methodand instrument for reading a lateral flow assay device which includes adetection zone in which a visually perceptible colorimetric change mayoccur, the instrument and method comparing images of the detection zoneof the assay device against sample readings of human visual perceptionsof colorimetric changes of reference assay devices in a stored databaseto determine whether the assay device detects the presence, absence orquantity of an analyte in a tested fluid sample.

In accordance with one form of the present invention, an instrument forreading a lateral flow assay device is provided. The lateral flow assaydevice performs an assay to determine the presence, absence or quantityof an analyte in a fluid sample. The assay device is placed in opticalproximity to the instrument, and further has a sample deposit zone onwhich the fluid sample to be tested is placed. The assay device furtherhas a detection zone in which a visually perceptible colorimetric changemay occur when the assay device detects the presence, absence orquantity of an analyte in the fluid sample.

The instrument of the present invention includes an optics module. Theoptics module has at least one camera which is positioned on theinstrument to view the detection zone of the assay device placed inoptical proximity to the instrument. The at least one camera generatesan output signal which is representative of an image of the detectionzone of the assay device and which is indicative of a colorimetricchange in the detection zone of the assay device.

The instrument of the present invention further includes a signalprocessor in electrical communication with the optics module. The signalprocessor receives the output signal from the at least one camera, andconverts the signal into measured colorimetric data.

The instrument of the present invention also includes a storage memorythat is in electrical communication with the signal processor. Thestorage memory has stored therein a dataset of sample readings ofreference assay devices similar in structure and function to that of theassay device read by the instrument. These sample readings are based onhuman visual perceptions of colorimetric changes in the detection zonesof the reference assay devices.

A comparator circuit, forming part of the instrument of the presentinvention, is in electrical communication with the signal processor. Thecomparator circuit compares the measured colorimetric data relating tothe assay device read by the instrument with the stored dataset ofsample readings based on human visual perceptions of the colorimetricchanges of the reference assay devices. Then, the comparator circuitgenerates a comparison signal in response thereto.

The signal processor receives this comparison signal from the comparatorcircuit and in response thereto generates a determination signalindicative of the presence, absence or quantity of an analyte in thefluid sample tested by the assay device read by the instrument.

In an alternative embodiment of the present invention, the optics moduleof the instrument may include at least one light source and a lightdetector. The at least one light source emits light and is positioned onthe instrument to direct the light onto the detection zone of the assaydevice placed in optical proximity to the instrument. The light detectorreceives reflected or fluoresced light emanating from the detection zoneof the assay device in response to the light directed thereon by the atleast one light source. The light detector generates an output signal inresponse to the reflected or fluoresced light received by the lightdetector, the output signal being indicative of a colorimetric change inthe detection zone of the assay device. This output signal is providedto the signal processor of the instrument.

As stated previously, a method for reading a lateral flow assay deviceby detecting color changes thereto based on human perception is alsodisclosed. The method includes the steps of placing the assay device inoptical proximity to an assay reader, such as described previously, suchthat the detection zone of the assay device is viewable by the at leastone camera of the assay reader. The method further includes the step ofgenerating an output signal by the at least one camera, which outputsignal is representative of an image of the detection zone of the assaydevice and which is indicative of a colorimetric change in the detectionzone of the assay device.

Then, in accordance with the method of the present invention, the outputsignal from the at least one camera is received by the signal processorof the assay reader. The method then includes the step of converting theoutput signal from the at least one camera by the signal processor intomeasured colorimetric data. The comparator circuit of the assay readerthen compares the measured colorimetric data relating to the assaydevice read by the assay reader with the dataset of sample readingsbased on human visual perceptions of the colorimetric changes of thereference assay devices stored in the storage memory of the assayreader.

In further accordance with the method of the present invention, thecomparator circuit generates a comparison signal in response tocomparing the measured colorimetric data with the stored dataset. Thecomparison signal from the comparator circuit is received by the signalprocessor, and, in accordance with the method, the signal processorgenerates a determination signal in response to the received comparisonsignal indicative of the presence, absence or quantity of an analyte inthe fluid sample tested by the assay device read by the assay reader.

These and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofillustrative embodiments thereof, which is to be read in connection withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a portion of a lateral flow assay device and,in particular, a SNAP® assay device manufactured by IDEXX Laboratories,Inc., and showing the read area on the device and several detectionzones forming part of the read area.

FIG. 2 is a perspective view of a SNAP® lateral flow assay device and areader formed in accordance with the present invention.

FIG. 3 is a top, side perspective view of a lateral flow assay devicereader formed in accordance with another form of the present invention.

FIG. 4 is a bottom, side perspective view of the lateral flow assaydevice reader of the present invention shown in FIG. 3.

FIG. 5 is a top, rear perspective view of the lateral flow assay devicereader of the present invention shown in FIGS. 3 and 4.

FIG. 6 is a block diagram of the optical and electronic components ofthe lateral flow assay device reader of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference should initially be had to FIG. 2 of the drawings. There, aSNAP® lateral flow assay device 2 is shown adjacent to the reader 16 forthe device 2 constructed in accordance with the present invention. Itshould be realized, of course, that the reader 16 of the presentinvention disclosed herein is not limited to use solely with a SNAP®assay device 2, and that the structure of the reader 16 and methoddisclosed herein may be used with many different types of lateral flowassay devices 2 on the market, including reversible (bi-directional)flow chromatographic binding assay devices, uni-directional lateral flowassay devices and lateral flow assay devices having colloidal goldparticles.

As shown in FIG. 2 of the drawings, the reader 16 of the presentinvention includes a housing 18 which is preferably in the form of arectangular parallelepiped having a sloping top surface 20 on which issituated a display 22 and a graphical user interface (GUI) 24 havingswitches or a keyboard 25 and indicators for inputting data and commandsand for receiving information concerning the tests being performed on alateral flow assay device 2, such as the SNAP® device. The display 22 ispreferably a liquid crystal display (LCD), which effectively provides anindication of what is displayed in the read area 4 of the assay device2, including a display of the detection zones 6, 8, 10, 12 and thecontrol portion 14 of the read area 4. The display 22 effectivelyrecreates what is shown on the read area 4 of the lateral flow assaydevice 2 being tested, which is viewed by the camera 26 of the reader 16in optical communication with the read area 4 of the assay device 2. Thehousing 18 includes an opening or a port 28 on one side thereof toclosely receive a lateral flow assay device 2, such as the SNAP® device.When received by the port 28, the lateral flow assay device 2 ismaintained in a position such that the camera 26 of the reader 16 is inoptical alignment with the detection zones 6, 8, 10, 12 of the read area4 on the assay device 2.

Another form of the lateral flow assay device reader 16 of the presentinvention is shown in FIGS. 3-5. These figures show a simplistic view ofthe assay reader 16, with the outer housing removed therefrom, tofacilitate an understanding of some of the major components of thereader 16.

More specifically, and referring to FIGS. 3-5 of the drawings, it can beseen that the lateral flow assay device reader 16 of the presentinvention is, like the reader 16 shown in FIG. 2, formed generally inthe shape of a rectangular parallelepiped. The reader 16 has an internalframe 30 having sidewalls 32, and a graphical user interface (GUI) 24 ispreferably mounted on one of the sidewalls of the frame, such as thefront sidewall 34. The GUI 24 is preferably sloped with respect to thesidewall 34 of the frame 30 on which it is mounted so that a display 22of the GUI 24 and any switches or keyboard 25, or other indicators, maybe easily viewed and accessed by a user of the assay reader 16.

As can be seen from FIGS. 3 and 4 of the drawings, one of the sidewalls32 of the frame 30, such as a lateral sidewall 36, includes a cutout toform a pocket 38 having a ledge or support surface 40 on which a lateralflow assay device 2 may rest. This pocket 38 formed in the frame 30 isin alignment with an opening formed in the outer housing (not shown) ofthe reader 16 so that a user may have access to the pocket 38 and placean assay device 2 within the confines of the pocket 38. The assay device2, when placed on the support surface 40 within the pocket 38, ismaintained in a position such that the read area 4 or window of theassay device 2 is in optical alignment with an optics module 42,preferably a camera 26, situated above it and mounted on the undersideof a printed circuit board 44 affixed to the frame 30. Preferably, thelateral flow assay device 2 includes calibration targets 46 in the formof markings or indicia which are placed in four corners surrounding theread window or area 4 of the lateral flow assay device 2. Thecalibration targets 46 are used to insure that the read window or area 4of the lateral flow assay device 2 placed within the pocket 38 of thereader 16 is in proper optical alignment with the optics module 42 ofthe reader 16. Preferably, the lateral flow assay device 2 furtherincludes a bar code 48 or other indicia to identify the type of assaydevice 2 placed in the reader 16, such as the SNAP® 4Dx® Plus assaydevice, the SNAP® Heartworm RT assay device, the SNAP® Feline Triple®assay device, the SNAP® FIV/FeLV Combo assay device, the SNAP® Parvoassay device, the SNAP® Giardia assay device, the SNAP® Lepto assaydevice, the SNAP® cPL™ assay device, the SNAP® fPL™ assay device and theSNAP® Feline proBNP assay device, each of which is manufactured ordistributed by IDEXX Laboratories, Inc. Clearly, other lateral flowdevice manufacturers can incorporate bar codes on their respectivedevices for proper identification.

The printed circuit board 44 referred to herein generally includes thecircuitry that comprises the signal processing unit 50 of the reader 16.The signal processing unit 50 includes a central processing unit (CPU)52, which carries out the operation of the reader 16 and its variousfunctions, and various memories, including a random access memory (RAM)54 and a read only memory (ROM) 56, as will be explained in greaterdetail. Some operational software is embedded in the RAM 54 and testdata is also stored therein, and the ROM 56 includes a database ordataset of sample readings of reference assay devices similar instructure and function to that of the assay device 2 read by the assayreader 16. The sample readings are based on human visual perceptions ofcolorimetric changes in the detection zones of the reference assaydevices.

The internal cavity, or pocket 38, of the frame 30 of the assay reader16 may include one or more diffuse reflectors 58 mounted on the internalsurfaces of the sidewalls 32 thereof to insure that any lightilluminating the lateral flow assay device 2 and emitted by one or morelight emitting devices, such as light emitting diodes (LEDs), or otherstructured lighting 60, is directed onto the read window or area 4 ofthe lateral flow assay device 2 situated within the pocket 38 of theassay reader 16. The LED lighting 60 is preferably mounted on theunderside of the printed circuit board 44 to direct light downwardlyonto the lateral flow assay device 2. The optics module 42 is alsomounted on the underside of the printed circuit board 44 and situatedabove the pocket 38 and a lateral flow assay device 2 received therein,and may include one or more cameras 26, as mentioned previously.

As can be seen from FIG. 5 of the drawings, the assay reader 16 mayinclude connectors or ports 62 for Ethernet or internet connections toexternal equipment. In the case of IDEXX Laboratories, Inc, this couldinclude connection to the IDEXX VetLab® Station which is capable ofcommunicating with other instruments, such as the VetTest™, CatalystDX™, Catalyst One™ and SediVue Dx™ analyzers manufactured or distributedby IDEXX Laboratories, Inc. These connectors 62 are preferably mountedon a rear sidewall 64 of the frame 30, or the outer housing, of theassay reader 16. Furthermore, the assay reader 16 includes a speaker ortransducer 66, also mounted on the rear sidewall 64 or another sidewall32 of either the outer housing or the internal frame 30 of the assayreader 18, to convey audible information to the user of the assay reader16. The speaker, or transducer 66, and the Ethernet and internet ports62 are electrically connected to the signal processing unit 50 of theassay reader 16.

FIG. 6 shows a block diagram of some of the electrical and opticalcomponents of the assay reader 16 of the present invention. As can beseen from FIG. 6, the assay reader 16 preferably includes an opticsmodule 42, as mentioned previously. The optics module 42 preferably hasat least one camera 26 that is positioned on the reader 16 to view thedetection zones 6, 8, 10, 12 (e.g., the “dots” mentioned earlier) in theread area 4 of the assay device 2 placed in optical proximity to theinstrument. The at least one camera 26 generates an output signal whichis representative of an image of the read area 4 and detection zones 6,8, 10, 12 of the assay device 2 and which is indicative of acolorimetric change in the detection zones 6, 8, 10, 12 of the assaydevice 2. Detection zones are not limited to “dots” but can includelines or other shapes where a capture reagent is disposed on the matrixupon which the sample flows.

As also mentioned previously, there is a signal processor 50 formingpart of the assay reader 16. This signal processor 50 is in electricalcommunication with the optics module 42. The signal processor 50receives the output signal from the at least one camera 26 and convertsthe signal into measured colorimetric data.

The assay reader 16 further includes a storage memory (such as the ROM56 mentioned earlier) that is in electrical communication with thesignal processor 50. The storage memory 56 has stored therein a datasetof sample readings of reference assay devices that are similar instructure and function to that of the assay device 2 read by theinstrument 16. The sample readings are based on human visual perceptionsof colorimetric changes in the detection zones of the reference assaydevices.

The assay reader 16 further includes a comparator circuit 68 which is inelectrical communication with the signal processor 50 and which may formpart of the signal processor 50. The comparator circuit 68 compares themeasured colorimetric data relating to the assay device 2 read by theinstrument 16 with the stored dataset or database of sample readingsbased on human visual perceptions of the colorimetric changes of thereference assay devices, and generates a comparison signal in responsethereto. The signal processor 50 receives the comparison signal from thecomparator circuit 68, and in response thereto, generates adetermination signal that is indicative of the presence, absence orquantity of an analyte (e.g., an antigen or an antibody) in the fluidsample tested by the assay device 2 read by the instrument 16.

As mentioned previously, the optics module 42 may include at least onecamera 26. However, in an alternative embodiment of the presentinvention, the optics module 42 of the assay reader 16 may include atleast one light source 60 and a light detector 70. The light source 60and light detector 70 may be formed, for example, as a reflectometer 72or a fluorometer 74. The at least one light source 60 emits light and ispositioned on the assay reader 16, such as on the underside of theoverhead printed circuit board 44, to direct the light onto thedetection zones 6, 8, 10, 12 of the read window 4 of the assay device 2placed in optical proximity to the reader 16. The light detector 70receives reflected or fluoresced light emanating from the detectionzones 6, 8, 10, 12 of the assay device 2 in response to the lightdirected thereon by the at least one light source 60. The light detector70 generates an output signal in response to the reflected or fluorescedlight received by the light detector 70. The output signal from thelight detector 70 is indicative of a colorimetric change in thedetection zones 6, 8, 10, 12 of the assay device 2. This output signalis provided to the signal processor 50 of the assay reader 16.

One of the important distinguishing features of the assay reader 16 ofthe present invention over other instruments used to read lateral flowassay devices 2 is that the assay reader 16 “mimics” what a human woulddo when perceiving whether there is a color change in the detection zoneor zones 6, 8, 10, 12 of the lateral flow assay device 2. In otherwords, the assay reader 16 of the present invention bases thedetermination of whether there is a colorimetric change in the detectionzone 6, 8, 10, 12 of the lateral flow assay device 2 that is indicativeof the presence, absence or quantity of an analyte in the fluid sampletested by the assay device 2 and read by the assay reader 16 based onhuman visual perception, and not based on an algorithmic rule whichmakes such determinations in conventional lateral flow assay devicereaders. The dataset or database of sample readings of reference assaydevices of similar function and structure to that of the assay device 2read by the assay reader 16 is, basically, a library of human visualcalls (i.e., determinations) to images from which their observationswere made. More specifically, in a specific embodiment, this storedlibrary of human visual observations preferably includes about 4million, or more, sample readings, or observations, made by humans ofsimilar lateral flow assay devices. For example, if a number of manualor human reads of images of lateral flow assay devices in the datasetstored in the memory 56 reflect a positive, or negative, determinationof crescent-shaped blue detection dots, or speckles instead of a fullcircular dot, or a light colored detection dot, then the comparatorcircuit 68 of the assay reader 16, and the signal processor 50 inelectrical communication therewith, will make a similar determination,based on the stored dataset of sample readings of human visualperceptions of the colorimetric changes of the reference assay devices.From this, the assay reader 16 of the present invention, and inparticular, the signal processor 50 thereof, generates a determinationsignal that is indicative of the presence or quantity, or absence, of ananalyte in the fluid sample tested by the assay device 2 read by theassay reader 16.

As further mentioned previously, a method for reading a lateral flowassay device 2 by detecting color changes thereto based on humanperception is also disclosed herein. The method is performed by alateral flow assay reader 16, which preferably has an optics module 42,a signal processor 50 in electrical communication with the optics module42, a storage memory 56 in electrical communication with the signalprocessor 50 and a comparator circuit 68 in electrical communicationwith the signal processor 50. The optics module 42 has at least onecamera 26. The storage memory 56 has stored therein a dataset of samplereadings of reference assay devices similar in structure and function tothat of the assay device 2 read by the assay reader 16. The samplereadings of the dataset are based on human visual perceptions ofcolorimetric changes in the detection zones of the reference assaydevices.

The method includes the step of placing the lateral flow assay device 2in optical proximity to the assay reader 16 such that the detection zone6, 8, 10, 12 of the assay device 2 is viewable by the at least onecamera 26 of the assay reader 16. Then, the method includes the step ofgenerating an output signal by the at least one camera 26 which isrepresentative of an image of the detection zone 6, 8, 10, 12 of theassay device 2 and which is indicative of a colorimetric change in thedetection zone 6, 8, 10, 12 of the assay device 2. The method furtherincludes the steps of receiving by the signal processor 50 of the assayreader 16 the output signal from the at least one camera 26, andconverting by the signal processor 50 the output signal from the atleast one camera 26 into measured colorimetric data. This measuredcolorimetric data is preferably stored in the RAM 54.

The method of the present invention further compares, using thecomparator circuit 68 of the assay reader 16, the measured colorimetricdata relating to the assay device 2 read by the assay reader 16 with thedataset of sample readings based on human visual perceptions of thecolorimetric changes of the reference assay devices stored in thestorage memory 56 of the assay device reader 16. Then, the methodincludes the steps of generating by the comparator circuit 68 acomparison signal in response to comparing the measured colorimetricdata with the stored dataset, receiving by the signal processor 50 thecomparison signal from the comparator circuit 68, and generating by thesignal processor 50 a determination signal in response to the receivedcomparison signal indicative of the presence, absence or quantity of ananalyte in the fluid sample tested by the assay device 2 read by theassay reader 16.

The at least one camera 26 of the assay reader 16 may be acharge-coupled device (CCD). However, and as mentioned previously, theoptics module 42 may use at least one light source 60, and a lightdetector 70 instead of the camera 26. Then, the method of the presentinvention would include the steps of directing light from the at leastone light source 60 of the optics module 42 of the assay reader 16 ontothe detection zone 6, 8, 10, 12 of the assay device 16, receiving by thelight detector 70 of the optics module 42 of the assay reader 16reflected or fluoresced light emanating from the detection zone 6, 8,10, 12 of the assay device 2 in response to the light directed thereonby the at least one light source 60, and generating by the lightdetector 70 an output signal in response to the received reflected orfluoresced light, the output signal being indicative of a colorimetricchange in the detection zone 6, 8, 10, 12 of the assay device 2. Thisoutput signal from the light detector 70 is provided to the signalprocessor 50 of the assay reader 16 and is converted by the signalprocessor 50 into measured colorimetric data.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various other changes and modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the invention.

What is claimed is:
 1. A method for reading a lateral flow assay deviceby detecting color changes thereto based on human perception, the methodbeing performed by a lateral flow assay reader, the assay reader havingan optics module, a signal processor in electrical communication withthe optics module, a storage memory in electrical communication with thesignal processor and a comparator circuit in electrical communicationwith the signal processor, the optics module having at least one lightsource and a light detector, the at least one light source emittinglight, the storage memory having stored therein a dataset of samplereadings of reference assay devices similar in structure and function tothat of the assay device read by the assay reader, the sample readingsbeing based on human visual perceptions of colorimetric changes in thedetection zones of the reference assay devices, the method comprisingthe steps of: placing the lateral flow assay device in optical proximityto the assay reader; directing light from the at least one light sourceof the optics module of the assay reader onto the detection zone of theassay device; receiving by the light detector of the optics module ofthe assay reader reflected or fluoresced light emanating from thedetection zone of the assay device in response to the light directedthereon by the at least one light source; generating by the lightdetector an output signal in response to the received reflected orfluoresced light, the output signal being indicative of a colorimetricchange in the detection zone of the assay device; receiving by thesignal processor of the assay reader the output signal from the lightdetector; converting by the signal processor the output signal from thelight detector into measured colorimetric data; comparing by thecomparator circuit of the assay reader the measured colorimetric datarelating to the assay device read by the assay reader with the datasetof sample readings based on human visual perceptions of the colorimetricchanges of the reference assay devices stored in the storage memory ofthe assay reader; generating by the comparator circuit a comparisonsignal in response to comparing the measured colorimetric data with thestored dataset; receiving by the signal processor the comparison signalfrom the comparator circuit; and generating by the signal processor adetermination signal in response to the received comparison signalindicative of the presence, absence or quantity of an analyte in thefluid sample tested by the assay device read by the assay reader.
 2. Amethod as defined by claim 1, wherein the assay reader includes ahousing, the housing having side walls defining an interior cavity, theoptics module, signal processor, storage memory and comparator circuitbeing situated within the interior cavity.
 3. A method as defined byclaim 2, wherein one of the side walls of the housing of the assayreader has formed therein a receptacle for at least partially receivingtherein the lateral flow assay device read by the assay reader, the atleast one light source and the light detector of the optics module ofthe assay reader being in optical communication with the receptacle andan assay device received thereby.
 4. A method as defined by claim 1,wherein the assay reader further includes a main housing, the mainhousing having side walls defining an interior cavity; wherein theoptics module is situated within the interior cavity of the main housingof the assay reader; and wherein the signal processor, storage memoryand comparator circuit are situated in a remote location from the mainhousing of the assay reader.
 5. A method for reading a lateral flowassay device by detecting color changes thereto based on humanperception, the method being performed by a lateral flow assay reader,the assay reader having an optics module, a signal processor inelectrical communication with the optics module, a storage memory inelectrical communication with the signal processor and a comparatorcircuit in electrical communication with the signal processor, theoptics module having at least one camera, the storage memory havingstored therein a dataset of sample readings of reference assay devicessimilar in structure and function to that of the assay device read bythe assay reader, the sample readings being based on human visualperceptions of colorimetric changes in the detection zones of thereference assay devices, the method comprising the steps of: placing thelateral flow assay device in optical proximity to the assay reader suchthat the detection zone of the assay device is viewable by the at leastone camera of the assay reader; generating by the at least one camera anoutput signal which is representative of an image of the detection zoneof the assay device and which is indicative of a colorimetric change inthe detection zone of the assay device; receiving by the signalprocessor of the assay reader the output signal from the at least onecamera; converting by the signal processor the output signal from the atleast one camera into measured colorimetric data; comparing by thecomparator circuit of the assay reader the measured colorimetric datarelating to the assay device read by the assay reader with the datasetof sample readings based on human visual perceptions of the colorimetricchanges of the reference assay devices stored in the storage memory ofthe assay reader; generating by the comparator circuit a comparisonsignal in response to comparing the measured colorimetric data with thestored dataset; receiving by the signal processor the comparison signalfrom the comparator circuit; and generating by the signal processor adetermination signal in response to the received comparison signalindicative of the presence, absence or quantity of an analyte in thefluid sample tested by the assay device read by the assay reader.
 6. Amethod as defined by claim 5, wherein the assay reader includes ahousing, the housing having side walls defining an interior cavity, theoptics module, signal processor, storage memory and comparator circuitbeing situated within the interior cavity.
 7. A method as defined byclaim 6, wherein one of the side walls of the housing of the assayreader has formed therein a receptacle for at least partially receivingtherein the lateral flow assay device read by the assay reader, the atleast one light source and the light detector of the optics module ofthe assay reader being in optical communication with the receptacle andan assay device received thereby.
 8. A method as defined by claim 5,wherein the assay reader further includes a main housing, the mainhousing having side walls defining an interior cavity; wherein theoptics module is situated within the interior cavity of the main housingof the assay reader; and wherein the signal processor, storage memoryand comparator circuit are situated in a remote location from the mainhousing of the assay reader.
 9. A method as defined by claim 5, whereinthe at least one camera of the assay reader is a charge-coupled device(CCD).
 10. The method of claim 1, wherein the lateral flow assay deviceis a reversible flow chromatographic binding assay device.
 11. Themethod of claim 1, wherein the lateral flow assay device comprisescolloidal gold particles.
 12. The method of claim 5, wherein the lateralflow assay device is a reversible flow chromatographic binding assaydevice.
 13. The method of claim 5, wherein the lateral flow assay devicecomprises colloidal gold particles.